Field of the Invention
The present invention relates to a power supply apparatus for converting an alternating current voltage to a direct current voltage, and an image forming apparatus including the power supply apparatus.
Description of the Related Art
In a conventional flyback switching power supply apparatus, the number of switching times of a switching element that switches the transformer is decreased in order to reduce power consumption, in a low load state. In Japanese Patent Application Laid-Open No. 2012-244878, the power consumption at a low load time is reduced by decreasing the number of switching times of a field effect transistor (FET) which is a switching element that switches the transformer.
However, when the number of switching times of the switching element is decreased, the number of switching times per unit time comes close to an audible frequency. Further, in the same load state, it is necessary to increase the amount of current that is passed to the switching element by switching at one time, so that there has been the problem that a beat noise is generated from the transformer. Further, when terminals are short-circuited due to an incidental failure of the switching element, an excessive current flows and is likely to break the peripheral elements.